Preparation of colloidal suspensions



manna-r alm nni Gar-ties Scott, Prince Bock, Plymouth England, aulgnor to Acheson Colloids Oorporation, Port Huron, Mich, a corporation of Iichi-j No mam. Applicationhpril z, 1940, Serial No.

327,542. In Great Britain April 14, 1939 4 I 7 Claims. (chase-2s) I I 'll'ie invention relatesv to the manufacture of According to the invention improved colloidal colloidal suspensions of solid lubricants. e. 8.

substances of crystalline structure having high cleavage and low cohesion in one or more di- 7 rections of the crystal lattice, such as graphite, mica, talc and the like materials, in non-aqueous media, for example in mineral oil, and in particular is concerned with the preparation of such suspension by transfer of colloidal suspension 10 of the substances from aqueous media to nonaqueous media.

Methods of transferring suspended material from aqueous to non-aqueous media are known and have been described in British patent specifications Nos. 27,312 of 1907 and 4,155 of 1912.

An example of a method of carrying out a transfer of suspended material from an aqueous medium to oil is as follows:

Powdered graphite is mixed with about 10-20 per cent. of a defiocculating agent, or protective colloid, such as tannin and the like, and with sufiicient water to make up a paste which can be ground in-a suitable mill. The paste is subjected to grinding, after which it is diluted and the coarser particles are separated from the colloidal particles by sedimentation, or other methods. The solution containing the colloidal particles is then concentrated by means of filter presses or otherwise. The resulting paste may contain approximately 50 per cent. solids and 50 per cent. water. The exact amount of water is, however, not critical. This paste is mixed with an equal part of an oil and the mass is agitated, whereby at a certain point water is exuded and is finally completely displaced by the oil.

There are certain difilculties arising in connection with transferring processes, the nature of which was not fully understood. It was found that not all oils are equally suitable for this transferring process, that in certain cases no separation of the water occurred and that in other cases where separtion occurred the resulting suspension of graphite in oil was not stable.

It is an object of the present invention to '4 provide an improved process of transferring suspended material from aqueous to non-aqueous media, whereby more consistent and satisfactory transfer is efi'ected.

It is a further object of the present invention to provide an improved transfer process whereby stable non-aqueous colloidal suspension of solid lubricants may be obtained.

' A further object of the invention is to provide a new transfer medium comprising electrionised vegetable oil.

suspensions in non-aqueous media are obtained by transfer of aqueous suspension to. a medium consisting of or comprising a vegetable oil which,

-with or without a diluent, has been subjected to 5 .the action of silent electric discharge.

.a suitable vegetable oil. Examples of other vegetable oils which may be used are:

Black mustard seed oil Soya bean oil 15 White mustard seed oil Sesame oil Linseed oil Cottonseed oil Sunflower oil Hempseed 011 Walnut oil The transfer medium may comprise the elec- 20 trionised oil in any proportion, for example up to 50%, the remainder being desirably mineral oil.

The following is an example of a convenient manner of carrying the invention into eflect, 25 as applied to colloidal suspensions of graphite.

An aqueous dispersion of graphite which may, for example, be prepared in the manner described above, is agitated with a quantity of Elektrion oil in the proportion ten parts of 30 aqueous graphite to four parts of Elektrion oil. After about half an hour of agitating the mixture, water separates from the mixture and the material is then worked for a further quarter of an hour approximately. No heat is employed 35 in this process, but after the separation the last traces of water are driven off by applying a vacuum and raising the temperature to between and F. The composition is then diluted by the addition of oil, which may be mineral oil or 40 Elektrion oil or a mixture of the two, so that the final graphite content is about 10% by weight.

An aqueous dispersion of graphite may in the same manner be transferred to a mixture of elec- Tung Oil trionised vegetable oil and a diluent in which 45 for example benzene, toluene and homologues, aliphatic hydrocarbons. ior example gasoline, kerosene, etc., chlorinated aliphatic or aromatic hydrocarbons, aicohols,

ethers. esters, etc.

Suspensions of other substances of crystalline structureghaving high cleavage" and low cohesion in one or" more directions or the crystal lattice,

ior ezarnplemica and talc, may be prepared in the manner described above.

I claim:

1. In the preparation of a colloidal suspension oi a solid lubricant in non-aqueous medium by transfer from an'aqueous suspension .0! the luspasms" z a graphite in-a non-adueousmedium wherein an aqueous colloidal suspension of sraphite is mechanically worked in the presence oi. vegetable oil which has been subjected to the action oi silent electric discharge. whereby to transier'the graphite from the aqueous medium to the said oiigand the-water is subsequently removed. a

4; In the preparation ot a colloidal suspension oi a solid. lubricant in non-aqueous medium-by transfer from an aqueous colloidal suspension, the improvement which consists in employing as the non-aqueous medium to which the transier is made a mixture 01' a) hydrocarbon diluent and vegetable oil which has been subjected to silentelectric discharge.

ii. The method claimed in claim 3 wherein the said vegetable oil which has been subjected to the action of silent electric discharge is employed in association with a-diluent.

6. The method claimed in claim 3 wherein the said vegetable oil which has been subjected to the action of silent electric discharge is employed in admixture with mineral oil.

7. The method claimedin claim 3 wherein the resulting suspension is heated to drive 01! the last traces of water.

LUCIANO GARTIEZ SCO'I'I'. 

